1. Field of the Invention
The present invention relates to a central control system of air conditioners and a method for operating the same, wherein a central control unit is connected to a plurality of air conditioners via a network to perform central control of the operations of the air conditioners, and an automatic operating algorithm is implemented in the central control unit for changing the operating mode of each of the air conditioners to limit the total peak power consumption of running air conditioners below a reference power value, which makes it possible to decrease the total peak power consumption of the building and the electricity costs, and also to prevent forcible power cut-off due to a rapid increase in power consumption.
2. Description of the Related Art
As use of air conditioners rapidly increases, air conditioners can now be found in each room of a residence or in each office of a building. An air conditioning system connected to a plurality of air conditioners via a network has also been provided recently.
One example of the air conditioning system is a single-type air conditioning system in which indoor units 11 are connected respectively with outdoor units 12 as shown in FIG. 1. Another example is a multi-type air conditioning system in which a larger number of indoor units 11 share a smaller number of outdoor units 12 provided in a single building or on a single floor, as shown in FIG. 2, to save installation resources and energy.
To provide cooling, the air conditioner 10 generally uses refrigerant that circulates in the indoor and outdoor units in a thermal cycle of compression, condensation, expansion and evaporation. On the other hand, a heat-pump air conditioner can provide cooling and heating by switching circulation directions of the refrigerant.
In the conventional air conditioning system, a control button mounted on the indoor unit or a remote controller allows a user to input a control command for power on/off, cooling/heating mode selection, blowing mode selection, control of the direction of discharged air, control of cooling/heating or blowing intensity, etc. Based on the input control command, a microcomputer embedded in the indoor unit controls the amount of refrigerant and the flow of refrigerant to perform indoor air conditioning.
If an error occurs in the operation of an air conditioner, a manager of the building personally goes to an indoor unit 11 or an outdoor unit 12 of the air conditioner to check the error, and then inputs a control command for maintenance and repair of the air conditioner.
In the case where one manager manages a plurality of air conditioners as in a school or a large building, the manager visits each room to input a control command and perform a manual maintenance and repair process of the air conditioner.
Some conventional air conditioning systems can perform central control of a plurality of air conditioners via a central control unit 20 that is connected to the plurality of air conditioners over a network via power lines or the like. However, such conventional air conditioning systems are provided with only a power lamp for checking the power state of each air conditioner and a power button for controlling the power of each air conditioner. The conventional systems cannot input a control command for controlling detailed operations of the air conditioner, and thus the central control unit 20 cannot be used for maintenance and repair when an error occurs in the operation of the air conditioner, which lowers the usability of the systems.
In particular, the air conditioner 10 has high power consumption for initial operation. In the case where a number of air conditioners are installed as in a large building, the total peak power consumption of the air conditioners is considerable in the normal operation also, raising a concern that the total peak power consumption exceeds the allowable limit of a power breaker (not shown) installed in the building.
If the total peak power consumption exceeds the allowable limit of the power breaker, the power breaker forces the entire power of the building to be cut off. The forcible power cutoff may cause a physical impact not only on a running air conditioner but also on other electric devices, thereby lowering endurance of the product.
An electricity supplier provides different upper power limits depending on seasons/buildings/service providers. If the total peak power consumption exceeds the upper power limits, the electricity supplier charges progressive electricity rates, which increases the burden of paying the electricity bills.